Selective ringing means for telephone systems.



E. E. CLEMENT.

SELECTIVE RINGING MEANS FOR TELEPHONE SYSTEMS.

APPLICATION FILED JAN. 18, 1907.

Patented Nov. 15, 1910.

2 SHEETS-SHEET l.

E. E. CLEMENT.

SELECTIVE RINGING MEANS FOR TELEPHONE SYSTEMS.

APPLICATION FILED JAN. 18, 1907.

Patented Nov. 15, 1910.

2 SHEBTSSHEET 2.

f] mum 1'04:

Wihmasea EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OFCOLUMEIA, ASSIGNOR TO THE NORTH ELECTRIC COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

SELECTIVE RINGING MEANS EOE TELEPHONE SYS TEMS.

Specification of Letters Patent.

Patented Nov. E5, 1910.

Application filed January 18, 1907. Serial No. 352,982.

To all whom it may concern:

Be it known that I, EDWARD E. CLEMENT, a citizen of the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Selective Ringing Means for Telephone Systems, of which the following is a specification, reference being had there in to the accompanying drawing.

My invention relates to telephone exchange systems and particularly to circuitsand apparatus for selective party-1111c ring- 'mg in such systems.

The object of the invention is to provide means whereby an A operator may select and apply any desired ringing current or ringing combination at a B position, the same as at her own position, without the B operator being required to do anything ex- .cept put up ,the desired connection. The A operator also supervises both at her own and the B end of the trunk, and signals the B operator for disconnection when she finally removesher plug from the trunk jack. 7

Hitherto, so far as I am aware, it has been necessary in =-trunking calls between exchanges for the B operator to complete the connection, and to select the current or combination pf circuits necessary to call a wanted subscriber if he be on a party line. It has been possible for the A operator to control -the ringing and to supervise the connection, but no more.

In the present invention, I make use of the principle of impulse transmission 'employed in automatic exchange systems, placing the selective switching apparatus at the B position and a suitable key or other impulse sender at the A position. The A op erator, desiring to ring a particular subscriber on the wanted line, sends a number of impulses designating that subscribers station over the trunk, thereby working the switching mechanism so that it will. connect the appropriate generator or circuits at the B position.

Specificallystated, and referring to a particular system of harmonic selection, I preferably place a set of step by step relays at the B exchange, coi'itrolling the circuits of four generators each adapted to furnish cur- 'rent suitable for ringing the bell at a particular station and no other. Any one of four stations on a line may be called by selecting and connecting the proper generator of this set to that line. At the A position I provide .the operator with a key or a set of transmitting keys, by means of which she can send 1, 2, 3 or timpulses over the trunk at will. When the connection is complete, she then transmits a proper number of'impulses' corresponding to the station she wants, whereupon one relay after the other is actuated until the generator is connected which will ring the desired station. The ringing relay then becomes energized and connects the generatorso selected through the trunk plug to the line, subject to being cut off. either when the wanted subscriber answers or otherwise in any suitable manner.

, My invention is not limited to manual systems but may obviously be applied without alteration toautomatic and semi-automatic systems. The most frequent application will be to branch exchange work, or what we may call clearing-house systems, wherein a main centraloffice is provided with manually operated switchboard apparatus, and the'branch exchanges are equipped with automatic apparatus adapted to be 0011- trolled through trunk linesirom the main office.

My invention is illustrated in the accompanying drawings in which Figure l is a diagram of a portion of the apparatus and circuits at a subscribers or A operators position; Fig. 2 is a similar diagram of a trunk line leading to a B position, with a portion of the apparatus at that position. D

Referring to the drawings in which the figures are complementary to Qach other, it will be apparent that the arrangement is based on the assumption of a call from substation A for a subscriber A, A A or IV,

the calling subscribers line terminating at one switchboard shown in Fig. 1, and the relay 1%, battery B and ground. lVhen the cut-ofii relay is energized the line is connected to its multiple jacks J, J.

P, P are the answering and calling plugs of a pair respectively, connected by the cord conductors 5-6 and 7-8. Two pairs of supervisory relays R R and R-R con'-' trol the circuits of the, supervisory lamps L, L, in a manner well understood by engineers. YVhere the connections effected through the cord are between lines terminating on the same switchboard, the cord circuit shown, with the four relays and the lamp, requires no change; but for my pres ent purpose of party line ringing control through the trunks, I provide a key K by which the tip relay B may be disconnected and the cord conductor 6 putv directly on the battery B. This disconnection of the tip supervisory relay prevents its energization when battery is connected, and thus avoids false signals. By tapping the key K, therefore, pulsations of current may be sent over the conductor 6 and thence through the tip of the plug P and over the tip side 15 of a trunk line 15-16 leading to a B board. I make use of these impulses for the purpose of selecting the ringing current to be applied to the called line.

Passing'to Fig. 2, the trunk 15-16 is divided by condensers G, and the calling end 17-48 thereof terminates on the plug P which is one of a set arranged before the B operator for connecting the trunks to the multiple jacks I -J of the wanted subscribers line. The incoming end of each trunk has relays RR both of whose circuits are controlled by the tip relay R and the sleeve relay R The supervisory lamp L which is intended for clearing out only, is also controlledby the relay R The ringing relay R is controlled jointly by the relay R and the driven commutator D which may be common to the exchange in which it is located, and may be driven in any suitable manner, as by a pawl and ratchet under control of a magnet fed from the main battery B, or by a motor. If desired, this commutator may be started bythe relays of any of the trunks, so as to be run 'ning only when it is needed.

The relay R controls the selective relays '1, 9'', r r 7 and '2' through the two wires 28 and 29, each movement back and forth "of thearmature of this controlling relay settin'gup an additional one of the relays r, r and 7' and thereby cutting off one generator and cutting on the next one.

The generators G, G, G and G are supposed. to be harmonic generators pro ducing current at different frequencies, and the ringers on the party line 48--il5) are bridged'across in parallel each being tuned to respond to one of the generators only. {Thus by selecting the proper generator, the

desired hell can be rung. It should be clearly understood however, that I am not limited to this harmonic method of ringing, since there are other methods which can be substituted in the present circuit without ditiiculty by any one familiar with the art,

and in fact, one virtue which I claim for my present system is that it may utilize any known system of ringing. For example, we will assume the normal generator con- .nection at G to be as shown across the wires 90 and 190. Then when the relay 1- is energized it may disconnect this generator and connect a generator of positive intermittent current to one side of line; relay 4' may connect the same to the other side of line, and so on. In fact, any desired combination of generatorsandringers may be effected through the agency of the selective relays I here describe.

The operation of the system thus described is as follows: Subscriber A calls in call to be for a subscriber A in another exchange, the A operator depresses an order key and thereby connects her own telephone to the telephone of a B operator at the other exchange, neither the order key and circuit nor the B operators telephone being shown herein, as they form no direct, part of the present invention and are well understood in the art. The B operator upon being given the number of the line wanted, answers back by designating the number of the trunk to be used. The A o erator then inserts the plug P into the designated jack J and if the line wanted is a party line she proceeds to tap the key K, unless the party wanted is the first party on the line, in which case the arrangement illustrated is normal and he will be automatically rung without any act on the part of the operator. When the plug P is inserted in the jack J 2 no current flows from the battery B through the trunk because the branches 20 and 24 are both open at the front contact of the armature r of the relay R The B operator, however, immediately inserts the plug P into the jackJ of the wanted line, after testing the same in the usual way. The. moment this is done, the following circuit is completed for the relay R B, 90, R 18, P, J, R, and ground back to battery. This pulls up both the relays R and R, the

latter being the cut-off relay of the line.

lowing circuits: 22, T11, 21, 20, R, 19, 15,

connection from ground through its armature 1- to the lamp Wire and the latter connecting the battery wire 10 to the armature of the relay R and thence to the supervisory lamp L.. Thus the lamp L will glow indicating to the A operator that connection is completed but the called subscriber has not yet answered, and this lamp will remain glowing until he does answer. The lamp L on the other hand, does not glow, since the B operator is not intended to supervise, and th s lamp is needed only for a clearing out signal.

The A'operator now taps the key K, as already stated.- VVe are assuming the party wanted is the third party on the line, whose bell is tuned to respond to current from the generator G The A operator presses down the key K twice. Eaehtime she does this, the battery B is connected through the trunk wire 15 to the relay R by the following path: B, 10, 11, 12, 6, P, J 15, 19, R 20, 21, 1- 22, and ground back to battery. The relay R, Which may be wound to a suitable resistance so that it will respond prop.- erly over any desired length of trunk and with any desired voltage, responds to each impulse by pulling. up its armature W, and

then releasing itvagain. Upon pulling it up for the first time, it closes-the followin circuit: B, 90, 27 r, 28, 80, r, and groun back to battery. The first relay 7 of the selective set thereupon pullsup, and byso doing connects the wire 27 directly to. its

own windings so as to lock itself up,vand

also connects the wire 29 to the Wire 37,

which leads through the armature of the relay 1 and its back contact to wire 35, and thence to the relay 1'. The wire 29, however, is open at this instant,,since it terminates at the back contact of 9, but it receives current as soon as that armature has fallen back after the first impulse from the operators key, over the fol- .lowing path: B, 90, 27, a, 29, 37,35, 7, and ground back to battery. The relay 7- immediately pulls up, locks itself through the wire 45 on to the wire 27, and also disconnects the wire 28 from the wire 30 and 'connects'it to the wire 32, leading to the second of what, I cal1 the guard relays, marked r thlrd'circuit change produced by this relay?" is the disconnection of the ringing wire 190 fromthe wire 40 leading to generator G, and its transfer to the wire 42 leading to the generator G.

As the armature r responds to the second the armature tion.

pulsation of current from the A operators key, the foregoing operations are repeated, except that instead of relay 1', it is the relay which responds to current through the wire and which looks itself up on wire 27 and at the same time transfers the wire 37 from the wire 35 to the wire 33, thereby connecting the relay r to the wire 29, so that it will obtain current through that wire when the armature 1' falls back again. As that occurs, the relay 1 is energized, locking 'itself on thewire 27, cutting the wire 190 off the generator G, and connecting it to the generator G There being no further impulses over the trunk, the relay R remains quiescent, and the generator G remains connected to the ringing relay contacts through the following path: 1', 190, armatures of relays 7' and 7*, wire 44, generator G wire 90, wire 91, and to the contact r through the resistance r, which is included because it'is necessary to keep the main battery B connected While ringing, in order to hold up the cut-off relay R. A similarly grounded resistance r is simultaneously included in circuit with the relay R", in order that it may also be held 'up.

The generator connections having now been prepared, the actual ringingis done in the following manner: The commutator D is constantly rotating, and as it rotates it grounds the relay R which is connected on the other side through the wires 26 and 27 to the front contact of armature r of the relay It, and thence through wire to bat tery B. The commutator 1) may be formed in any suitable manner, but I have shown it as half metal and half insulation, so as to produce equal intervals of silence and ring. Whenit completes the circuitof the relay R", the latter pulls in its armatures, -severing the cord conductors 17 and 18, and con-' necting the plug P through the forward fragments of the cord. to thecontacts r and r, whichare already connected to the generator G Current from this generator therefore passes out over the line wires 4849 and rings the bell at the desired st'a As the commutator rotates further, it cuts off the relay It", and for an interval the cord conductors are restored and then the subscriber A may reach and control the supervisory relay R. If he answers during this interval, or during any subsequent interval, the relay will pull up on current passing over the following circuit: B, 90, R, 1.8, P J 48, A 49, 17, R and ground back t'o'battery. The pulling up of relay R breaks the circuit of the ringing relay by separating the wires 26 and 27, disconnects the lamp L from the battery wire 27, and disconnects the wires 20 and 24 from the wire 21 which as we have already seen is at this time grounded. The effects are these: First, the ringing relay is not again supervisory lamp L cause its circuit is broken at the armature of relay R The A operator is thus advised that the called subscriber has answered. At

. the same time, the circuit of the lamp L is completed to the. armature 1" only, being broken at armature 1". Hence this lamp remains dark.

The battery supply for the line 4.8%?) is derived through the relays R and R from the battery 15, over the line frcuit already traced. The subscribers A and A. have control of the respective lamps i and L in the A operators'cord circuit, just the same as if they were. in the same exchange. When subscriber A hangs up his receiver, his relay R becomes decnergized and the lamp L glows. Similarly, when the subscriber A" hangs up his receiver his relay R lets go its armature, and completes the circuits of the relays R and R, whereupon the lamp L, in Fig. 1 again receives current and glows. The glowing of both the lamps L and L advertises to the Aoperator the desire of the subscribers for disconnection. The plugs P and P are thereupon taken down from the jacks. The effect of this at the B end is that the lamp L immediately glows, receiving current through the following circuit: battery l3,'90, 1", 27, 0", L 25, r, and ground. This advertises to the B operator the fact that the trunk is idle, and should be disconnected, whereupon she takes down the plug P, and 'as the relay R immediately lets go its arn'iature the lamp L goes out. At the same time, since current is removed from the wire 27 by the retraction of the armature r all the rela s 1" r, r r

r and 1" let go their armatures because they have lost their locking current, hence all of the generator connections are immediately restored to their normal condition ready for renewed operation. v

The ringing of subscribers by the A operator in her own exchange may be done with an ordinary ringing key, or in any other desired manner. This forms no part of the present invention, eXceptt-hat I may provide the same equipment for the cord circuit in' for the cord circuit in Fig. 2, the relays r, 0*, etc, having. their wires 28 and 29 )assing then direct to the key K, instead of to the contacts of the relay It. The key K in Fig. 1 that is shown such :ase would not be connected to the cord conductor 6,'but to the battery wirelO direct, so that, its operation would be precisely the same as that of the armature r in Fig. 2, the only dilierence being that it is moved by hand instead of by a magnet. The arrangement of the supervisory relay it in connection with the ringing relay It and the commutator D in in Fig. 1 goes out bepulses.

without departing such case would be precisely the same as the arrangment of relays R and R and commutator D in Fig. 2, so that I have not considered it necessary to illustrate this specific variety of the invention. It oes without saying that such selection WOUild not be as useful or necessary for direct key ringing at an A- position as it is at the B positions, because at the A positions we can run the generator wires 40, 42, 4st and 46 direct to the keys, without the intermediation of relays. However, there are cases in which it is desirable to have uniformity of apparatus and methods, and in such case I may apply this arrangement as stated.

For the sake of simplicity,I have shown a single key K which the operator presses down a number of times in order to select the desired generator. This key may be replaced in practice if desired by means for automatically sending any number ofim- Such means are too well known to need detailed descriptio For examples plurality of keys may be employed, each one pressed down against the tension of a spring, and directly making and breaking the contacts between the wires 11, 12 and 14, by means of teeth on its shank, or indirectly by means of. a toothed geared. This device may also be in the form of a dial transmitter, having a lever corresponding to the key K, moved by teeth on a spring drum, which is moved. forward wheel to which it is as many teeth as will correspond to the number desired to be transmitted. Still another form might have the same toothed wheel, and a setting arm it could be turned, and when released re turned by its spring, moving the contacts a number of times equal to the number of teeth turned around in setting. For further examples I may refer to the entire class of variable signal dial .transmitters,-under fire telegraphy.

I am aware that sundry changes may be made in the system I have thus described, from the spirit of my invention, and I take this occasion to state 'that I contemplate all suchchanges as within the scope of my claims, believing this invention to be broadly novel and original with me. v

Having thus described my invention what I claim and desire to secure by Letters Patent is:

L'A'trunk ringing system for telephone exchanges comprising means controlled by an A ope'ator for connecting a calling subscriber with a trunk line, n1eans at aB or trunking station for conneetingthe trunk with the-wanted su'bscribers line, said line serving more than; one subscribers station, a selective signaling device at each station, a plurality of generating devices with the B switching position,

and autoassociatedfixed to it whereby trolled by A operators for matic means controlled through the trunk line by the A operator for selectingand connecting the proper generator to ring the bell at the desired station, substantially as described.

In a telephone exchange system, subscribers lines terminating in different switchboards, a trunk line interconnecting said switchboards, an A operators connective apparatus for connecting a calling line through the trunk with a called line terminating on the other or B switchboard, selec tive ringing apparatus at the B board, and selective actuating devices at the A board controlling the same through the trunk line,

substantially as described. v

3. In a telephone exchange system, a. plu- .rality of subscribers lines terminating at different central ottices, and trunk lines interconnecting the central offices, means conconnecting said trunk lines with calling subscribers lines, means controlled by B operators for connecting the trunk lines with'wanted subscribers lines,.switching means for selectively ringing the bells at any one of several stations on the same line, with separate setting means -for selectively controlling the same through a trunk line when connected, substantially as described. v

4:. In a telephone exchange system, subscribers lines terminating on jacks in two diii'erent exchanges, a trunk line interconnecting the exchanges, means associated with the trunk line for supplying selective ringing current thereto tor use incallingover party lines, impulse actuated switching means cooperating therewith for selective purposes, and a selective impulse transmitter associated with each' answering or A op- 'erators apparatus, adapted to be connected through a trunk when in, use to the said switching means, substantiallyas described.

5. In a telephone exchange system, a plurality of subscribers lines terminating on jacks at different central oflices,a 'trunk line extending between said offices and terminating at one end in a jack and at the other in a lug, Aoperators cord circuits for connecting calling subscribers jacks with the-trunk jack,'an impulse transmitter associated with one or more of said cordci'rcuits, means for generating current 'for selective ringing over party lines, and, selective switching devices associated with theplug terminaluof the trunlrfor determining the ringing current to be applied thereto, said switching devices adapted to be controlled over the trunk .by said impulse transmitter, substantially as described. 4

6. In a telephone exchange system,- a trunk line between exchanges for interconnecting subscribers lines terminating at the .difierent exchanges, a selective transmitter associated with the originating end of said matic switching device for applying the same selectively to a called line when the trunk is connected thereto, a relay associated with the trunk and controlling said switching device and an A operators impulse transmitter for controlling said relay through the trunk, substantially as describe v 8. In a telephone exchange system, sub-- scribers lines terminating on jacks in difforent central otlices, a trunk line extending between the oflices, an A operators cord circuit and terminal plugs for connecting a calling line jack with the trunk, an impulse transmitter connected with. said cord circuit, a relay responsive thereto-connected to the 13 end of the trunk, selective generating means also at the B end of the trunk, auto-' matic switching devices therefor responsive to said relay, and automatic means for applying a selected ringing current to the called line when the selection has been made, substantially as described. i

9. In a telephone exchange system, subscribers linesterminating in different central oflices', a trunk line interconnecting the .central ofiices, a' ringing selector at the B end of the trunk, an operators cord cir cuit and supervisory signal at the A endgof'the trunk, an operators; transmitter device "for controlling the ringing selector, associated with said cord circuit, and means for dis-- abling the supervisory. signal while said transmitting device is being operated, s'ub stantially as described.

10. In a telephone exchange system, sub- I scribers lines terminating at di'fier nt ofiices and a trunk line interconnecting't e offices,

A operators connective apparatus for connecting a calling subscriber with the trunk,

supervisory signals associated therewith,

means for, connect-ingthe B end of the trunki with a wanted subscribersline, a ringing selector associated with sa'id 'means, a' clearing out signal also associated with said means, an actuating device for said ringing selector, associated with the A openato'rs connective apparatus, and relays associated with sa d connect ve apparatus and with the trunk responsive to the act'of the called subscriber and adapted to-gontrol the ringing, substantially as described.

11. In a telephone exchange systgem, subscribers" lines terminating at different offices and a trunk line interconnecting the office's,

A operators connective apparatus for connecti'nga calling subscriber with the trunk, supervisory signals assoclated tl'ICI'GWliLh,

means for connecting the B end of the trunk with a wanted subscribers line, a ringing selector associated with said means, a clearing out signal also associated with said means, an actuating device for said ringing selector, associated with the A. operators connective apparatus, and relays associated with said connective apparatus and with the trunk responsive to the act of the called subscriber and adapted to control the A operators supervisory signal and the ringing, whereby ringing current will be removed from the called line and the operator apprised thereof when the subscriber answers, substantially as described.

12. In a telephone exchange system, trunk ringing means comprising an operators se-' lective transmitter, a ringnw selector responsive thereto at the B end 0t each trunk, and relays associated with the B end of the trunk for connecting the ringing generator, and responsive to the act of the called subscriber for disconnecting said ringing gen erator, substantially as described.

13. In a telephone exchange system, trunk ringing means comprising the following instrumentalities: an A operators cord circuit and an impulse transmitter connected thereto, a plurality of selective ringing generato s at the B end of the trunk with automatic s\vitcl1i11gniei 1ns responsive to the A operators transmitter to select any one of said generators, a ringing relay and a commutator controlling the same for connecting the selected generator to the called line, and

a trunk relay responsive to the act of the called subscriber to control said ringing relay, substantially as described.

In testimony whereof I aifix my signature in presence of two witnesses.

- EDVIARD E. CLEMENT. ll itnesses E. EnMoNsroN, Jr., JAMES H. MARK. 

